<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Promise Learing - 练习题</title>
    <style type="text/css">
		#traffic-light {
			border-radius: 50%;
			width: 4rem;
			height: 4rem;
			/* background: #333; */
		}
	</style>
</head>
<body>
    <H3>Please open console to see the execute process</H3>
	<div id="traffic-light"></div>
    
    <script src="./index.js"></script>
</body>
</html>